Here's my thought: the presentation would have several battle trailers for new fighters and mechanics, but each time one ends they use it to segway into the next presentation. 

For example, the presentation would start with Inkling versus new Link versus Mario gameplay of Smash, which would show off some of the basics of the game like graphics and a new stage and mechanics before a fourth character joins the fray. For example, Yoshi. 

After Yoshi appears, we go into Yoshi Switch trailer. 

After Yoshi's trailer, another battle starts up, and the next reveal would be signaled by a corresponding fighting dropping in. 

For example Xenoblade DLC news would be heralded by Shulk or a Rex/Phyra reveal, Pikmin 4  by Olimar, and Star Fox Grand Prix by Fox. 

Or is this a horribly unorganized and unpleasant format to do it in?

I think that would make the presentation awful for people who don't like Smash, don't get me wrong, I'd love it, but you also have to think about people who are not fans.

Imho the best way to show it off (assuming it's a totally new game) is giving it 5-8 minutes at the beginning of the presentation, then showing everything else they have, then closing with a big game that is going to have a new rep in Smash. Imho the most fitting would be Metroid Prime 4: they show 2 minutes of gameplay/CGI giving it context and stuff, then they show 2019, then the Smash logo appears and they announce Ridley/some other new character is now in Smash

Here's hoping Elma gets some love too. Would love to have her in Smash.

theyre using Smash Bros heavily in the advertisements but it not a Smash-focused presentation. it will show off many new games in addition to Smash

Smash is not going to have that many trailers in the presentation. What will most likely happen is the presentation starts and ends with Smash, and then we get new character reveals throughout the rest of the days.